Induction-coil.



T. L. LEE.

mnucnou con.

APPLICATION FILED NOV- 1.1917.

1,274,428. Patented Aug. 6, 1918.

a H H n flnwenmra 3W 42.421.

UNITED STATES PATENT oEEIoE.

THOMAS I4. LEE, OF ROCHESTER, NEW YORK, ASSIGNOR TO NORTH EAST ELECTRIC COM- PANY, OI ROCHESTER, NEW YORK, A CORPORATIONOF NEW YORK.

INDUCTION-COIL.

Specification of Letters Patent.

' Patented Aug. 6, 1918.

This invention relates to induction-coils of the Ruhmkorfi' type, and is particularly applicable to such induction-coils when used for the purpose of ignition in connection with internal-combustion-engines.

One object of the invention is to provide an improved construction for connecting the insulated terminal of the secondary winding with a conductor external to the casing in which the windings are inclosed. The construction by which this is accomplished is adapted particularly for use when such casing is of metal, and therefore conductive, and it comprises a plug, of insulating-material, removably inserted in an opening in the casing and provided with a' contact-spring for engagement with the secondary terminal.

Another object of the invention is to provide, in a simple and convenient way, a safety spark-gap for the passage, in emergencies, of the secondary discharge of the coil. A spark-gap for this purpose is provided in connection with the insulating plug aforesaid and the metal casing of the coil, as will be more fully described hereinafter.

In the accompanying drawings Figure 1 is a front-elevation of an induction-coil em-v bodying the present invention, with the easing and the terminal-plug in section; and Fig. 2 is a vertical sectional view of the casing, on the line 22 in Fig. 1, showing the terminal-plug in place.

The invention is illustrated as embodied in an induction-coil having the usual concentric cylindrical windings 5, which are inclosed in a casing 6. The illustrated 0011 has a magnetic circuit of peculiar form. which is not claimed as a part of the present invention, and which need not, therefore, be described further than to state that it has the effect of substantially eliminating stray magnetic lines of force, and thus normally closed by a cover 7, and in assembling the structure the coil-proper is introduced through this top-opening. To facilitate assembling the parts in this manner,

and to provide the necessary insulation of y the secondary terminal and its connections from the conductive metal casing, the novel construction characteristic of the present invention is used.

The casing 6 is provided With a wide lateral aperture, through a screw threaded neck 8. Into this neck a plug 9 of insulating-material is screwed, a gasket 11 being used to make a water-tight joint between the neck 8 and the peripheral lip 10 of the plug.

A binding-post 12 is fixed in the middle of the plug'9, preferably by molding it into the material. This post receives the wire 13 by which the high-tension discharge is conducted away from the coil, and the wire is shown as attached to the binding-post by means of a nut 14, in the usual manner.

The insulated terminal of the secondary winding of the coil has the form of a button 15 mounted on. the outer surface of the coilproper, in line with the binding-post 12. As a convenient means for connecting these parts, the binding-post is provided, at its inner end, with a socket 16 (Fig. 2) in which a small coil-spring 17 is loosely mounted. After the coil-proper hasbeen fixed in place in the casing the plug 9 is screwed in place, thus pressing the spring 17 against the terminal 15 and making connection between the terminal and the binding-post.

To provide the safety spark-gap before referred to, a disk 18 of sheet-metal is fixed concentrically upon the inner end of the binding-post. The periphery of the disk approaches to within safe sparking distance of the screw-threads on the inner surface of the neck 8, and since the periphery and the threads are concentric, and therefore equidistant at all points, an indefinite number of points are provided between which the discharge may take place.

It has been found that Where a spark occurs close to the surface of a body of insulating-material the discharge has a tendency to follow such surface, with the effect of burning and channeling the surface if the body be of bakelite, rubber, or other combustible material. To prevent such injury to the plug 9 in the present instance, the inner surface of the plug is provided with concentric corrugations 19. This has the effect of so lengthening the path which would have to be followed by a discharge along this surface, that the discharge will pass, by preferenc'epdirectly through the airgap between the disk 18 and the casing.

The invention is not limited to the embodiment thereof hereinbefore described and illustrated in the accompanying-drawings, but it may be embodied in various other forms within the scope of the following claims.

The invention claimed is:

1. In an induction-coil, the combination of a metal casing provided with a terminalopening; an insulating bushing closing said opening; a high-tension binding-post mounted on said bushing; and a lateral projection, on said binding-post, extending to within safe sparking distance from the casing at the periphery of said opening therein.

2. In an induction-coil, the combination of a metal casing provided with a terminalopening; an insulating bushing closing said opening; a conductor for high-tension current passing through the bushing; and a conductive member, on said conductor, projecting therefrom toward the periphery of said opening and to within safe sparkin distance from the casing, at a plurality of points substantially equi-distant from the casing.

3.. In an induction-coil, as in claim 1, corrugations in that surface of the said insulating bushing which is adjacent the point of discharge between the said projection and the caslng, whereby the discharge is prevented from following said surface.

4. In an induction-coil, the combination of primary and seconda windings; an insulated secondary terminal mounted laterally upon the windings; a metal casing inclosing the windings and provided with a lateral opening substantially concentric with said terminal; an insulating bushing removably inserted in said opening; a binding-post 'mounted on said bushing and having a socket at its inner end, and a contact-spring mounted in the socket in the binding-post and normally engaging said terminal and affording an electric connection between the terminal and the binding-post.

5. In an induction-coil, as in claim 4, a metal disk fixed concentrically upon the inner end of the binding-post and projecting, at its periphery, to within safe sparking dis tance from the casing at the periphery of the said opening.

THOMAS L. LEE. 

